On-line gradient liquid chromatography-Fourier transform infrared spectrometry determination of sugars in beverages using chemometric background correction

An on-line gradient reversed phase liquid chromatography-Fourier transform infrared spectrometry (LC-FTIR) method was developed for the determination of fructose, glucose, sucrose and maltose in beverages. Improved chromatographic resolution was obtained using a linear gradient from 75 to 55% (v/v) acetonitrile in water in 15 min. Changes in the background spectra were corrected employing “univariate background correction based on the use of a reference spectra matrix” (UBC-RSM) and using the ratio of absorbance (AR) at 2256 and 2253 cm⁻¹ for the identification of the eluent spectra within the RSM. The method provided limits of detection in the order of 0.75 mg ml⁻¹. The precision (as relative standard deviation) ranged between 3.3 and 4.1% for glucose and fructose, respectively at a concentration level of 3.0 mg ml⁻¹. Quantitative recovery values on spiked samples confirmed the accuracy of the method. A set of samples from the Spanish market were analysed to test the suitability of the procedure.